Hydraulic operator



Feb. 27,1940. s 2,191,888

' HYDRAULIC OPERATOR I Filed Dec. 2, 1936 I 4 Sheets-Sheet 2 4/ 4: E 87|68 5 67 8.5 a/ 73 65 63672 75 7/ y INVENTOR. ar/d P /-/////4 BYATTORNEY.

Feb. 27, 194-0. D s 2,191,888

HYDRAULIC OPERATOR I Filed Dec. 2, 1936 4 Sheets-Sheet 3 INVENTOR.

Z0); 7 //////5 BY "ATTORNEY.

Patented Feb. 21, 1946 2, 3 I I UNITED STATES PATENT OFFICE" HYDRAULICOPERATOR David R. Hillis, Detroit, Mich., aasignor, by

' mesne assignments, to Reconstruction Finance Corporation, Detroit,Mich, a corporation oi the United States Application December 2,1936,=Seriai No. 113,873

' 13 Claims. (Ci. 121- 157) My invention pertains to fluid pressuremotors a hydraulic ope a o e abo e type wh rein and more particularly toa hydraulic operator for the piston actuated valve is actuated throu hactuating parts of machinery, valves, pumps and slack motion drivingmeans interconnected from the like. the piston, and interlocking meansis actuated by It is an object of my invention to provide a, movement ofthe piston driven valve and of the 5 rugged, compact, hydraulic operatorof positive other va ve in response to the app e fl p esoperatingcharacteristics, which can be made of sures whereby Simultaneous51111111118 1 h V v simplified construction and few moving parts. '1 p vIt is also an object of my invention to provide a The novel featuresthat I consider characters 1 hydraulic operator comprising a casinghaving istic of my invention are set forth with particuan inlet and anoutlet port, a fluid pressure relaflty in the p n c im The inventionsponsive operator member movably disposed in itself. h w v r, bOth as toits lm r c n and the casing for movement by high pressure fl id itsmethod of operation, together with additional applied in the inlet portto generate working objects and advantages thereof, will best beunpower, and fluid responsive valve .means for conderstood from thefollowing descriptions of spe- 15 trolling the application of thepressure fluid from ciflc embodiments, when read in connection with theinlet port to reversely move the operator the accomp ny g drawin s,inwhich: member. 1 Fig. 1 is a side elevational view of my hydraulic Itis a further object of my invention to proopera vide such a hydraulicoperator having fluid con- Fig. 2 is a longitudinal sectional view takenon 20 ducting means controlled by the movements of line ll h o show theco-bpera iv the working operator for applying fluid pressure relation ofthe movable parts disposed therein;

7 from the inlet port to reversely move the fluid Fig. 3 is'a similarview showing the movable responsive valve. elements of the device indifferent positions;

, 2 Another object of my invention is t provide Figs. 4 and 5 arecross-sectional views taken hydraulic operator of the above type havinginon section lines 4-4 and lines 5-5 respectively terlocking meansactuated by the movements of as shown in Fig. .3; the operator memberfor interlocking with and Fig- 6 s Side elevational w Showing 91controlling the movements of the said fluid presother embodiment of myhydraulic operator; so sure responsive valve. Figs. 7 and 8 aretransverse sectional views A further object of my invention is theprothereof taken on section lines 1-! and 8-8 revision of such ahydraulic operator wherein the spectively as shown in Fig. 6; workingoperator member is a hollow piston or Fig. 9 is a longitudinal sectionalview taken sleeve having its fluid pressure controlling valvetherethrough on line 9-9 as shown in Fig. 7; slidably carried thereinfor establishing fluid con- Fig. 10 is a lon nal ctional view takenducting connections to reversely move the hollow therethrough O linelop-lo 88 shown in ig- 8;

piston, fluid conducting ports and passages conand trolled by the hollowpiston to apply fluid pre- Fig. 11 is a similar view showing the movablesures for reversely moving the valve, an intervalves disposed intheiralternative operative polocking pin slidabl-y disposed in the hollowpissitions therein. 40, ton for engaging at one end with either one ofReferring m p lly to Figs. 1-5 of the two interlocking. recesses in thevalve and at its dr win I v tr ively disclosed anemother end engagingsuitable camming surfaces in bodiment of my improved hydraulic operatorthe casing for locking the fluid responsive valve in comprising ahousing or casing I, which may be either one of two extreme positionsduring prea casting of any suitable metal. The casing is 5 determinedmovements of the hollow operator provided with an inlet port 3 forreceiving any piston. working medium or fluid from any source, or uni-Another object of my invention is to provide a flow system, which'provides a supply -of the hydraulic operator comprising, a fluidpressure working fluid under suitable pressure conditions.

responsive piston, a fluid responsive valve for An outlet port 5 is alsoprovided in the casing applying fluid pressure to reversely operate thefor discharging the working fluid, which may piston, and a piston drivenvalve for applying return into a reservoir, if the device is'used in afluid pressures to reversely move the fluid recontinuous circuit system.The ports 3 and 5 Sponsive V are passages provided by drilling into thecasting Also it is an object of my invention to provide I axially, andpreferably from opposite ends, to 66 facilitate connection of thehydraulic operator into a system. for which purpose each port isprovided with internal threads i.

To generate power for useful work, a fluid pressure responsive operatormember, comprising a hollow piston 9, is slidably disposed in acylindrical aperture H which extends axially through the casing.The'piston guiding aperture II is provided by boring axially through thecasing,-

and the opposite ends are internally threaded to receive fluid flowrestricting heads or plugs l3 and Id. The cylinder head plugs areprovided at the outer ends with laterally, projecting shoulders II whichare of hexagonal, or other suitable form, for receiving a wrench forturning the plugs into the casing firmly for sealing the ends of thebore. Also the plugs i5 and I! extend suitably into the cylindrical boreH for properly limiting the extreme positions of the hollow piston 9therein.

The operator piston 9 may be formed by tuming a piece of metal ofsuitable cylindrical dimensions and boring the same axially, or atubular sleeve may be utilized, and internal threads are provided atopposite ends of the piston to threadably receive plugs I9 and 2|therein. Each ally extended hexagonal head 23 on the outer end foroperatively receiving a wrench.

For applying the high pressure working fluid from the inlet aperture 3to reversely move the operator piston 9, I provide a plurality of spacedinlet ports 25 and 27 connecting from the inlet aperture 3 through theside walls of the piston guiding bore adjacent opposite ends thereof. Athird inlet port 29 connects from the inlet passage 3 through the sidewalls of the piston guiding bore II at a point substantially in themiddle thereof. The port apertures 25, 21 and 29 may be provided bydrilling through from the outer surface of the casing and thereafterclosing the portion of each bore, which extends from the inlet passage 3to the outer surface of the casing, by a metallic plug secured thereinas by threading or welding in any suitable manner, as will be readilyunderstood.

The hollow operator piston 9 is provided wi ports 3|, 33 and 35 whichpierce the side walls thereof for operatively connecting with properones of the stationary ports 25, 29 and 21 in the casing as the pistonslides therein.v For this purpose, the end piston ports 3| and 35connect selectively with the stationary ports 25 and 21 as the pistonmoves to one end or the other in the casing. In the outer surface of thepiston 9 a groove 39 is cut axially connecting into the central pistonport 33 to provide continuous connection fromthe central inlet port 29in the casing as the piston slides to and fro.

For controlling the flow of working fluid into and through the hollowpiston sleeve 9, I provide a piston valve 9| of the dumb-bell typeslidably disposed therein. The piston valve comprises fluid flowrestricting valve heads 93, 95, 31 and 59 which slide snugly in closefitting relation in the bore 5| of the hollow piston 9. The flow restricting heads of the siidable valve 98 are conheated in spacedrelation by connecting rods 53, 59 and 51 of reduced cross-sectionwhereby fluid can flow freely between them. The intermediate portion ofthe central connecting rod 59 is enlarged to provide interlocln'ngrecesses 59 and St at opposite ends thereof, but its diameter is lessthan that of the bore 5| so that fluid can pass freely around it. Theend heads 93 and d9 of the sliding valve ii carry outwardly projectingstops 93' which serve to abut the inner ends of the plugs l9 or 2| toaccurately determine the end positions of the valve, in proper relationto the ports connecting through the side walls of the piston sleeve 9,and to avoid obstruction of the end ports therein.

The movement of the sliding valve 4| in the hollow piston 9 iscontrolled by fluidpressures applied on the ends of the valve, and alsoby an interlock which prevents simultaneous shifting of the hollowoperator piston and of the sliding valve in response to the fluidpressures applied thereon. For this purpose an interlocking pin 63 isprovided which is slidably disposed in a suitable aperture. The pin isof greater length than said aperture and in order to accommodate it, twospaced camming recesses 65 and 61 are provided in the cylindrical boreof the casing at points diametrically opposite port 33 in each of itsextreme positions.

Thus, when the valve 4| starts to move, the enlargement will force thepin 63 upwardly into one of the camming surfaces 65 or 61 to preventmovement of the hollow piston 9 at the same time and converselywhen theparts are in proper position for the shifting of the hollow piston 9,the movement of said piston will cause the camming surfaces 65 or 61 toforce the pin 63 downwardly into the proper interlocking recess 59 or 6|in the valve 4|, thus preventing it from shifting at the same time. Theends of the interlocking pin are rounded for smooth engagement in therespective recesses.

Additional ports 69 and II are provided, piercing the side walls of theslidable operator piston sleeve "9, adjacent the ends thereof, at pointsspaced correspondingly to the end piston ports 3| and 35 previouslydescribed. A pair of intermediatespaced ports 13 and 15 are provided inthe side walls of the piston 9 and grooves Ti and 19 are provided intheouter surface of the piston extending axially from their outer ends forcontinuous connection with stationary ports 8| and 83 respectively whichare provided in the casing for connecting into the outlet passage 5.Also connecting from the outlet passage 5 in the casing are ports 85 and81 which pierce the side walls of the piston guiding bore atpointssuitend port 69 or H in the piston 9. w 1 v For providing additionalfluid discharging con-,

' ably spaced for connecting selectively with either nections, thepiston ports 69, -and '|3 with groove sleeve thereof is provided with apassage 88 drilled from said end axially therein, as represented bydotted lines, to a point slightly beyond the cen' ter and thenceconnected through a radial portion which opensinto the hollow piston andcon prises a valve controlled'port 99. Similarly, for discharging fluidto apply an operating pressure upon the opposite end of the piston 9-apassage 92 is drilled axially therein and connects into the pistonthrough a valve controlled portSd;

For guiding the slidable operator piston 9- and I preventing rotation ofthe piston, a guide pin 99 projects from one side into which-it maybe r9,191,888 secured by threading, or.in any other suitable manner. .The@uterend of the guide pin-39 pro- Jects into a guide groove 9|. ofsuitable conformation, cut axially at a suitable position in thesidewalls of the piston guiding bore II. Rotation of the piston beingthus prevented, the operative connection of the piston ports with theproper casing ports is provided, and the outer end of theinterlocklng'pin 93 is properly engaged by the camming recesses 35 and 91 in thecasing as the piston reciprocates.

For operatively connecting the slidable operator piston 9 with anymechanical device to be thereby actuated, a-piston rod,-or operator rod,

93 is secured at its innerend to one of the pis-.

ton plugs 2I in any suitable manner, as by welding or threading thereto.The operator rod 93 extends from the casing through one of the cylinderheadplugs I5 which is suitably apertured. The outer portion of theaperture in the head plug I5 is counter-bored to a larger diameter toprovide a packing gland 95 to receive packing 99 which is compressedaround the slidable operator ing previously shifted said valve. Frominlet pas-' sage 3 fluid flows through ports 29 and 33 into the hollowpiston, thence around the reduced connecting portion 55 at the middle ofthe valve and by way of port .99 and passage 83 into the space at theleft hand end of the piston.

The pressure thus admitted moves the hollow piston to the right, and itsinitial movement earns the interlocking pin 53 downto hold the valve 4 IThe groove 39 provides continuous-connection of the inlet port 3 throughthe port 29 with the port 33 in all positions of the piston and thefluid pressure is continuouslyap'plied in the middle of .the piston.Hence fluid continues to flow, as

traced above, and the piston is moved to its extremeright hand positionabutting the head plug I5, asshown in Fig. 3, but the valve M will stillbe in its right hand position.

As the port 25 is now closed, fluid will pass through ports 21 and 35into the hollow piston and shift valve 4i to the left, as shown in Fig.3, its first movement causing the interlocking pin 93 to be raised sothat its outer end is received in camming recess 91, thus preventing itfrom shifting at the same time. This is not so important duringoperation of the parts, but very important when the pressure has beendiscontinued and is then reapplied, as it prevents the parts fromstopping on dead center.

The movement .of the valve 4I to its left-hand position completed theconnections for applying the pressure of the working fluid to the righthand end of the piston which will be thereby returned to its left handposition. For this operation the fluid flows from the inlet passage 3 byway of ports 29, and 33, through the hollow piston around the restrictedmiddle portion 55 of the valve 4I, thence by way of port 94 and passsage92 into the space at the right hand end of the piston. ,as the pistonbegins to move, its' initial movement depresses the interlocking pin 93thus holding the valve 4I till the-movement is completed. During thisoperation the axial groove 39 provides continuous connection between theports29 and 33. The movement of the piston 9 completed to the left, theouter end of the pin 93 enters recess 95 in the casing being raised bytheinitial movement of the valve H in the reverse direction.

The above cycle of operations is repeated successively, so longasworking fluid of a suitable pressure is supplied to the inlet port 3,and the operator rod 93 is thus reciprocated by the piston for actuatingany pump, valve, or other mechanically movable element-which is to beeontrolledthereby.

In accordance with another embodiment of my invention, as shown in Figs.6-11, a casing MI is provided with a large aperture or piston guidingbore I93 extending therethrough and smaller,-

valve receiving, apertures I95 and II" drilled therethrough, in spacedrelation and preferably parallel thereto to provide a unit which iscompact and conveniently connectable. The casing I9I is preferably asuitable casting comprising an elongated base I92, integral therewith.The

base I92 is provided with a pedestal portion I94 upon which my hydraulicoperator may be mounted in any desired location.

In this embodiment of my hydraulic operator, the movable operator memberto translating the pressure of the working'fluid i' to mechanicalmotionfor doing useful work comprises a piston I99 slidably disposed inthe piston guiding bore I93. The operator piston I99 comprises asubstantially cylindrical body of. a suitable diameter for slidingfreely in the cylindrical aperture I93, and it is provided with a pistonrod, or operating shaft III, which is connected, as by threading orwelding, to one end thereof. The piston rod IIIprojects for connectionwith any mechanical element to be actuated thereby. The ends of thepiston guiding cylinder I93 are provided with internal threads foroperatively receiving a cylinder head plug H3 in one end thereofcomprising alaterally projected shoulder I Iii-which may be of hexagonalor other suitable conformation for receiving a wrench, by which it'isconveniently installed or removed. In the other end of. thepiston'guiding bore I I93 9, cylinder head plug I I1 is threadablysecured, which comprises an outwardly projecting sleeve 9' having anenlarged counter-bore I2I extended therein to provide a packingglandwherein packing material I22 is flrmlycompressed aroundthe operatorshaft III by means of a packing ring I23. For compressing the packingtoward the rod III the inner end of the pack ring I23 is suitablytapered and a wide flange I25 is provided upon the outer end forengagement by a packing'nut I21, which is internallythreaded .to bereceived upon external I threads provided upon the packing sleeve II9.

A fluid responsive piston valve I29, is slidably disposed inthe valvereceiving aperture I91 for ate connector I is of larger diameter thanthe other connectors to provide interlocking recesses m and m, which aredisposed at the ends of u rod I63.

the connector adjacent the heads I83 and I35 re spectively. The valvebore I01 is provided with internal threads adjacent the oppositeends-thereof for receiving suitably threaded plugs I49, which are turnedflrmly therein to seal the ends of the aperture, and also to providelimiting stops for the valve. Projecting outwardly from the outer endsof the valve heads I3I and I31 are suitable stops I5I provided forabutting the adjacent plugs I49 to thereby limit the position of theslidable valve I29 in spaced relation from the ends of the bore I01.

The piston controlling valve I29 is in turn operated by fluid pressuresapplied alternately to the ends thereof, in accordance with themovements of a piston .driven valve I53 which is slidably disposed inthe aperture I05. The piston driven valve I53 comprises flow restrictingheads I55, and I51, connected in spaced relation by a connector I59 ofreduced cross section to provide for the free flow of fluid around it.At one end the head I53 is joined thru a connector I6I, of reduced crosssection, to the inner end of a valve The valve actuating rod I63projects outwardly from the end of the aperture I05 through a packingfixture I65 which comprises a suitable packing gland and nut forproviding a slidable seal around the rod. From the valve head I55, atthe opposite end of the valve, a reduced connector I61 is joined to theinner end of a rod I69 which projects from the opposite end of the boreI05 through a suitable packing fixture I1I. Upon the outer end of thestop rod I69 an annular ring I13 may be firmly secured,

in any suitable manner, as by threadable en-- gagement thereon, by whichthe relative position of the connected valve may be readily ascertainedwhen it is desired to adjust the adjustable stops adjustably thereon asby a clamping bolt I3I on each side for drawing up a clamp I82. Theupper portion of the actuator I19 extends upwardly from the piston rodadjacent the valve rod I63 betweenthe stops I15 and I11 thereon. Thus asthe piston rod is slidably operated by its piston, the actuator I19alternatively engages the stops on the valve rod to throw the valve I53to its alternative positions after any desired predetermined movement ofthe piston rod has been completed.

In its operation the piston driven valve I53 controls fluid conductingmeans for reversely operating fluid responsive valve I29, as will besubsequently set forth, and a mechanical interlock is provided whichprohibits both valves from shifting simultaneously. For this purpose,'Iprovide a slidable interlocking pin I83, which is slidably disposed inan aperture I85, which extends directly between the center points of thevalve apertures I05 and I01 in the casing. The interlocking pin I83 isprovided with rounded ends which are thus disposed for operativelyengaging recesses I81 and I89, which are provided in the driven valveI53 as well as the interlocking recesses I45 and I41 provided in thefluid responsive valve I29.

The pin is longer than the aperture I85 in which it is mounted. Hence,whenever one valve moves, it forces the adjacent end of .the pin out ofits recess, causing it to project into the other ale- 517 valveaperture,being received inone of the re cesses of the other valve. Thus it isimpossible for both valves to move. simultaneously and the valves canneverstop on dead center.

Working fluid enters the casing IOI under pressure from a suitablesource such, as a pipe line I9I which is threadably connected into theouter end of an inlet port I 93 and, as shown in Figs. 10 and 11, passesthrough a passage I95 into the valve bore I05, at substantially themiddle thereof. Fluid pressure is thus continuously applied in the spacebetween the valve heads I55 and I51 of the valve I53. The valve'isarranged to reciprocate through a distance which is slightly less thanthe distance. between the heads. From the mid-point of the valve guidingbore I05, a passage I96 continuously connects, as shown in Figs. 8 and9, into the mid-point of. the valve guiding bore I01, whereby the linepressure is also continuously applied into the space between the headsI33 and I35 of the fluid "responsive valve I29.

From the centrally charged .space in the driven valve I53, high pressurefluid is discharged through,a passage I99, into the left hand end of thevalve guiding bore I01, as shown dotted in Fig. 10. Hence driving thevalve I53 to the right tends also to move the fluid responsive valve I29in the same direction. The passage I99 connects into the valve bore I05at a point suitably disposed to the right of the center to be controlledby thevalve head I51 for successive connection with inlet port pressuresevery time the driven valve I53 is moved to the right.

When the driven valve I53 moves to the left, its head I55 uncovers theport of a passage 20I, shown dotted in Figs. 10 and 11, which extendsthe right hand end of the valve guiding bore I01 and the fluidresponsive valve I29 is thus moved to the left, as shown in Fig. 11. Thestops I5I on the ends of fluid responsive valve I29 serve to stop it inspaced relation from the end plugs I49 whereby the fluid can enterfreely from either passage I99 or 20I to quickly throw the valve I29 toits alternative position.

' The reciprocating motion thus imparted to the valve I29 discharges thehigh pressure working fluid from the space between the heads I33 and I35alternatively through passages 203 or 205 into the respective right handor left hand end of the piston guiding aperture I03, as shown in Fig. 9.The opening ports of the passages 203 and 205 are suitably disposed inbore I01 for control by the movements of the valve heads I33 and I35respectively whereby movement of the -fluid responsive valve I29 to theright, passes fluid through passage 205 to drive the piston I09 to theleft, and vice versa.

The passages 203 and 205, connecting to the ends of the piston guidingbore I03, serve alternatively for intake and exhaust. As shown in Fig.9, fluid is being discharged through passage 205 to 'move the piston I09to the left. As this operation takes place, the fluid previously chargedinto the cylinder at the left of the piston I09 is now exhausted throughpassage 203 into valve bore I01, from which it passes through an exhaustpassage 201, into an outlet port 209. The outer end of the outlet port209 is threaded for connection with a pipe 2 which discharges theexhaust fluid, as it returns to the line, if the hydraulic operator isused in a closed system. A corresponding exhaust passage 2I3 isinterconnected between the valve receiving apertures I05 through thecasing IOI and discharges fluid into and I01, correspondingfluidpressure oneness connection withthe passage ill to receive fluidexhausted by the return stroke of the piston.

Directly above the passage III, is a e 2", connecting the valvereceiving apertures I" to port til. Thus, exhaust from the right ofvalve receivins aperture lll'l returns through passage Ill into valvereceiving aperture III, as seen in Fig. 10, thence through passage til mthroush valve receiving aperture lfl between "heads iti and la, thenceout through es 201,120! and 2.

As the piston III! is thus operated from side to side it in turn drivesthe'valve I! through the slack motion connectors Ill and ill. .Themotion of the driven valve II! from end to end of its bore It! appliesfluid pressures-to opposite ends of the fluid responsive valve it.through the fluid conducting connections'thus established and thereafterreleases the interlock. This in turn reciprocates the fluid responsivevalve it! in its 1 bore to apply reverse operating fluid pressures to inturn reversely operate the piston i". Operating cycles comprising theabove operations continue successively so long as suitablefluidpressures are applied in the inlet port "I.

It will be seen acting hydraulic operator of and few moving parts.

Aside from the speciflc embodiments of the invention herein shown anddescribed, it will be understood that numerous details of the con-.-

from the inlet port Ill that I have provided a positive simpleconstructions struction may be altered or omitted without departing fromthe -spirit and scope of the invention as disclosed and claimed, andthat I do not desire to limit the invention to the exact constructionsherein set forth. I claim: 1

.1. In a hydraulic operator for use in uniflow systems the combinationof, a casing having an inlet port and an voutlet port, a fluid pressureresponsive operator member movably'disposed in said casing, fluidresponsive valve means movable in said casing for controlling theapplication of pressure fluid from the inlet port to reversely move saidoperator member, and an 1 interlock actuated by the movements of saidoperator member for interlocking with and con-.

"fluid pressure systems trolling the movements of said fluid responsivevalve means. I

2. In a hydraulic operator for use in uniflow the. combination of, acasing having an inlet port and an outlet port, a fluid pressureresponsive operator member movably disposed in said casing, fluidresponsive and an outlet valve means movable'in said casing forcontrollingthe application of pressure fluid from the inlet port toreversely move said operator member, fluid conducting means controlledby the movements of said operator member for applying fluid pressurefrom the inlet port to reversely move said fluid responsive valve means,and an interlock actuated by the movements of said operator member forinterlocking with and controlling the movementsof said fluid responsivevalve means.

3. In a hydraulic operator for use in uniflow fluid pressure systems thecombination of, a casing, a substantially'cylindrical aperture in saidcasing, a fluid responsive operator member slidin: said operator member.an

to reversely move said of said operator member trolled by pressures .toreversely move the valve therein,

stir disp e said casing for receiving outlet port in said casing fordischarging fluid therefrom, a fluid responsive valve movable in saidcasing for controlling the application of fluid pressure from said inletport into opposite ends of said recess operator member, fluid conductingmeans controlled by the movements of said operator member for applyingfluid pressure from the inlet port to reversely move said valve, and aninterlocking pin actuated by the movements of said slidable operatormember for interlocking with and controlling the movements of saidfluidresponsive valve means.

4. In a hydraulicoperator for use in uniflow fluid pressure systems thecombination of. a casin saidaperture, aninlet port in pressure fluid formow ing, a substantially cylindrical aperturein said casing, a fluidresponsive operator member slidably disposed in said aperture, an inletport in said casing for receiving pressure fluid for moving saidoperator membe an outlet port in said casing for discharging fluidtherefrom, a fluid responsive valve movable in said casing forcontrollinmthe application of fluid pressure from said inlet port intoopposite ends of said recess to reversely move said. operator member,fluid conducting means controlled by the movements for applying fluidpressure from the inlet port to reversely move said valve, twointerlocking recesses 'in said fluid responsive valve corresponding toits extreme positions, an interlocking pin slidably disposed to projectone end thereof into either one of said interlocking recesses, andcamming means controlled by the movements of the operating member forengaging the other end of said interlocking pin to interlock and controlthe movements of said valve inresponse to the fluid pressures appliedthere 5. In a fluid pressure actuated operator the combination of, acasing having an inlet port port, an aperture in said casing, a hollowoperator piston perture, fluid responsive valve means carried in saidhollow piston for establishing fluid conducting connections to reverselymove the hollow piston, fluid conducting ports and passages conthehollow piston for applyin fluid cammins surfaces in said casing, and aninterlocking member carried by said hollow piston to engage said cammingsurfaces for limiting. the movements ,of said valve means in said hollowpiston in response to the fluid pressures applied thereto. e

6. In a fluid pressure actuated operator the slidably disposed in said 7combination of, a casing having an inlet port i and an'outlet port, anaperture in said casing, a hollow operator piston slidably disposed insaid aperture, fluid responsive valve means carried in said hollowpiston for establishing fluid conducting connections to reversely movethe hollow piston, fluid conducting ports and. passages controlled bythe hollow piston for applying fluid pressures to reversely move thevalve therein, two interlocking recesses in said valve, an interlockingpin slidably disposed in said piston for engaging at one end with eitherone of said recesses in said valve, camming surfaces in said casing forengaging the other end of said interlocking pin as the piston moves inthe casing to lock the fluid responsive valve in either one of twoextreme positions during predetermined movements of the hollow operatorpiston.

, combination of, a casing, a cylinder bore extending through saidcasing, an inlet port for receiving working fluid in said casin anoutlet port for discharging exhaust fluid from said casing, fluidconducting passages connecting said ports into said bore, an operatorsleeve slidably in said bore, a dumb-bell piston valve slidably disposedin said sleeve for applying fluid pressures to reversely operate saidoperator sleeve, flow retricting plugs inserted in the ends of said boreand said sleeve, fluid conducting means controlled by the operatorsleeve for applying fluid pressures to reversely move the valve therein,two interlocking recesses in said valve, an inter locking pin slidablydisposed in the side wall of said operator sleeve for engaging at oneend in either one of said recesses, camming surfaces in the side wall ofsaid bore for engaging the other end of-said interlocking pin as theoperator sleeve slides to either end of the bore to lock the fluidresponsive valve in either one of two extreme positions duringpredetermined movements of the operator sleeve.

8. In a fluid pressure, actuated operator the combination of, a casing,a fluid pressure responsive operator piston slidably disposed therein,,a fluid responsive valve for applying fluid pressures to reversely movesaid operator piston, a driven valve for applying fluid pressures toreversely move said fluid responsive valve, slack motion driving meansinterconnected between said operator piston and said driving valve, andlocking means for locking the fluid responsive valve while the drivenvalve is moving.

9. In a fluid pressure actuated operator the combination of, a casing, afluid pressure responsive operator piston slidably disposed therein, afluid responsive valve for applying fluid pressures to reversely movesaid operator piston, a driven valve for applying fluid pressures toreversely move said fluid responsive valve, means for driving saiddriven valve comprising a slack motion connection, two locking recessesin said fluid responsive valve, two camming recesses in said drivenvalve, and a locking pin slidably disposed in said casing for selectiveoperative engagement by said camming recesses at one end and forselectively engaging into either one of said locking recesses at theother end whereby simultaneous movement of the fluid responsive valveand the driven valve is eliminated.

10. In a' hydraulic operator for use in uniflow fluid pressure systemsthe combination of, a cas- 1 ing having an inlet port and an outletport, a fluid pressure responsive operator member disposed in saidcasing for movement in response to fluid pressure supplied through saidinlet port, fluid responsive valve means movable in said casing forcontrolling the application of pressure fluid from the inlet port toreversely move the operator member, means controlled by the movements ofsaid operator member for applying fluid pressure to reversely move saidfluid responsive valve means, and locking means controlled in accordancewith the movements of said operator member and said fluid responsivevalve means to prevent stoppage on dead center.

11. In a hydraulic operator for use in uniflow 1 by the movements ofsaid operator member forapplying unexpansible fluid pressure from theinlet port to reversely move said pressure responsive valve, two spacedlocking recesses in said pressure responsive valve, a locking pinslidably disposed for engaging said locking recesses selectively forholding said valve ineither one of two extreme positions, and cammingmeans for actuating said pin to lock said valve during a portion of themovement of said operator member.

12. In a hydraulic operator for use in uniflow fluid pressure systemsthe combination of, a casing having an inlet port and an outlet port, ahydraulically operated pressure responsive operator piston slidablydisposed in said casing, a piston valve of the dumb-bell type, a guidebore for slidably supporting said valve, fluid conducting passagescontrolled by said valve for controlling the application ofincompressible pressure fluid from the inlet port to reversely move saidoperator member, fluid flow controlling means controlled by themovements of said operator member for applying unexpansible fluidpressure from the inlet port to reversely move said pressure responsivevalve, two axially spaced locking recesses in said pressureresponsivevalve, a locking pin slidably disposed for engaging said lockingrecesses selectively for holding said valve in either one oi two extremepositions, and camming means for actuating said pin to lock said valveduring a portion of the movement of said operator member.

13. In a fluid pressure actuated operator" the combination of, a casinghaving an inlet port and an outlet port, a fluid pressure responsiveoperator piston, a bore in said casing for slidably receiving saidpiston, a first dumb-bell type piston valve, 9. second dumb-bell typepiston valve, bores in said casing of suitable diameter for slidablyreceiving said valves therein, fluid conducting ports controlled by thefirst valve for applying fluid pressures from the inlet port toreversely operate said operator piston, fluid conducting portscontrolled by the second valve for applying-fluid pressures to reverselyoperate the flrst valve, a slack motion mechanism for driving saidsecond valve from the operator piston, a pair of locking aperturesaxially spaced on the first mentioned valve, camming surfaces axiallyspaced on the second valve, a locking pin, an aperture in said casingfor slidably receiving said pin and so arranged that one end of the pinis selectively engaged by the camming surfaces for causing the other endof the pin to selectively engage the spaced locking apertures

